The selective grammar school came top in the 2017 Secondary Real Schools Guide - is billed as the most comprehensive guide ever to state-funded secondaries.

Put together by the Trinity Mirror Data Unit, the unique rating system uses 50 different measures, put together from the latest publicly-available data and broken into four categories – attainment, progress, attendance, and outcomes.

National league tables may only look at overall GCSE results, as well as newer measures such as Attainment 8 and Progress 8, which may mean schools that help all pupils make progress, but only get slightly better than average exam scores overall, may be overlooked.

This system aims to move beyond more limited measurements and give parents a better idea of which schools will help their child prosper, no matter what their background may be.

The guide factors in other things as well - like whether all pupils are making progress, what attendance is like, the ratio of teachers to pupils, and whether students go on to further education or jobs.

Attainment is worth 30 per cent of the total score. This based on pupils' average Attainment 8 score, including what the average scores for different groups of pupils were, as well as the proportions gaining the English Baccalaureate and those getting A* to C grades in GCSE subjects. We measure whether a school is getting top marks, and if it is managing to improve year-on-year.

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Here are the top schools in greater Plymouth area according to the Real Schools Guide

Devonport High School for Girls - score of 74

Ivybridge Community College - 62

Launceston College - 60

Plymstock School - 58

Ridgeway School - 56

Devonport High School for Boys - 54

Hele's Trust - 53

Plymouth High School for Girls - 50

Callington Community College - 50

Lipson Co-operative Academy - 49

How the ratings work

Devonport High School for Girls pupils received their A level results last year. Pictured: Beth Blackwell, Georgia Valentine, Josie Russell and Atlanta Foster

Progress is worth 40 per cent of the score. It is based on how well all as well as different types of pupil do on the Progress 8 measure, as well as whether the school is adding value when it comes to subjects such as science and languages. It also looks at things that may contribute to teaching outcomes, such as how big the pupil/teacher ratio is in comparison to the national average, as well as teachers' average salaries.

The attendance score is based on absence rates, looking at both overall levels of sessions missed as well as unauthorised and persistent absence at the school. It is worth 15 per cent of the total score. Outcomes is also worth 15 per cent, and is based on what proportion of pupils continue with education after Year 11 or go on to training and work, as well as what proportion drop out of employment, education or training - in comparison to the national average.

Different measures are given weightings based on how important they are likely to be to parents – so the pupils' average Attainment 8 and Progress 8 scores are worth a maximum of eight points, while the difference between average teacher salary and national average is worth just 0.75.

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Scores are worked out by giving the best performing school in each category top marks, with all other schools receiving points adjusted according to their comparative performance. Schools where performance is below average can receive negative points up to a maximum of –0.5.

Scores for each measure are then added together to get a total score for each category, and all the scores are added together to get a total. This total is adjusted to ensure no school can receive a negative total.

Stars are allocated by rating all the scores in order for each indicator and then splitting schools into five equally-sized groups.

Not all schools have data for every measure. Some schools are so tiny that the data has been suppressed to avoid identifying pupils.

Schools are not penalised for not having data, and only schools with below-average performance can receive negative points. However, not having data means a school cannot score extra points for that measure, potentially putting them behind schools that do not have missing data. Schools that had no Year 11 pupils taking GCSEs in 2016 are not rated.